1. Field of the Invention
The present invention relates generally to increasing the number of optical fiber terminations that can be obtained from a fiber optic cable, and more specifically, to a preterminated fiber optic cable including an optical splitter positioned adjacent a downstream end of the cable that is operable for back-feeding optical fibers terminated at an upstream access location.
2. Technical Background
Optical fiber is increasingly being used for a variety of broadband applications including voice, video and data transmissions. As a result of the ever-increasing demand for broadband communications, fiber optic networks typically include a large number of access locations at which one or more optical fibers are terminated and branched from a distribution cable. These mid-span access locations provide a branch point from the distribution cable leading to an end user, commonly referred to as a subscriber, and thus, may be used to extend an optical communications network closer to the subscriber. In this regard, fiber optic networks are being developed that deliver “fiber-to-the-curb” (FTTC), “fiber-to-the-business” (FTTB), “fiber-to-the-home” (FTTH), or “fiber-to-the-premises” (FTTP), referred to generically as “FTTx.”
Conventionally, in order to create a mid-span access location along a length of fiber optic distribution cable, a field technician was required to remove a portion of the cable sheath in the field at a convenient location along the length of an installed distribution cable. Once the sheath was removed, the technician accessed pre-selected optical fibers, severed the pre-selected optical fibers and removed a length of the optical fibers from the distribution cable. The removed length of optical fiber provided the field technician with adequate length to splice one or more optical fibers of a cable comprising a lesser amount of optical fibers than the distribution cable, typically termed a “drop cable,” to the distribution cable optical fibers. After all splicing was completed, the access location was typically covered using a rigid enclosure designed to protect the splices and the exposed section of the distribution cable. This time consuming process was typically accomplished by a highly skilled field technician at a significant cost and under less than ideal working conditions.
With the development of FTTx, improved methods of creating mid-span access locations have been introduced that overcome the disadvantages of accessing optical fibers in the field. In one such approach, predetermined access locations are formed and drop cables are spliced to the distribution cable at a factory during the manufacturing of the cable. This “preterminated” cable, including the distribution cable, drop cables and any associated splice closures, are assembled and wound onto a cable reel to be delivered to an installation site. Accordingly, factory conditions for making high quality splices are utilized, thereby increasing splice quality and also reducing the expense and difficulty associated with field splicing. Further approaches eliminate the splicing of the drop cables to the distribution cable, and instead provide preterminated and/or pre-connectorized fiber optic distribution cables having one or more mid-span access locations formed at predetermined positions along the length of the cable. Each mid-span access location provides a plurality of readily accessible optical fibers that may be spliced or otherwise optically connected (e.g., via fiber optic connectors) to drop cables at the time of service installation following deployment of the distribution cable. Advantages of this type of factory-prepared cable assembly include a reduction in the field labor required to establish optical connections and improved quality of the splice connections.
In each of the cable assembly examples described above, a common element is the incorporation of one or more mid-span access locations positioned along the length of the cable that allows access to a plurality of terminated optical fibers of the distribution cable. In all examples, terminating one or a plurality of the optical fibers at a predetermined mid-span access location naturally results in the length of optical fiber downstream of the mid-span access becoming unusable, and therefore wasted. In other words, by terminating an optical fiber that runs the length of the distribution cable at a predetermined position along the length of the distribution cable in order to provide a branch point, the optical fiber must be cut, and the cut results in the portion of optical fiber downstream of the branch point being “dark” or “dead”.
Accordingly, it would be desirable to provide a means for utilizing these downstream portions of optical fibers in order to increase the number of optical fiber terminations that can be obtained from a preterminated fiber optic cable. It would also be desirable to provide a preterminated fiber optic distribution cable including one or more predetermined access locations having factory preterminated optical fibers along a length of the distribution cable and a means for utilizing the downstream portions of the cut optical fibers to thereby increase the number of optical fiber terminations that can be obtained from the fiber optic cable. The terminated optical fibers that are re-used expand the capacity of the distribution cable by providing a greater number of optical fiber terminations potentially available from the same cable. The cut optical fibers may also be used as spare optical fiber terminations as needed. It would also be desirable to provide a preterminated fiber optic distribution cable including a downstream splitter, while still maintaining discrete fiber capability and achieving a low-profile for deployment over sheave wheels and through relatively small diameter conduits. Further, using the cut optical fibers has several obvious advantages including reduced cable material costs, reduced cable size and reduced splicing complexity.